Is Your Garden Hungry for Sulfur?
Cleaner air may be leaving your plants hungry
Billions of dollars have been spent making the air we breathe cleaner. We may be breathing better, but soil tests indicate that gardeners and farmers will have to add sulfur (S) to the list of nutrients that need to be added as a fertilizer.
One of the major components in polluted air was sulfur dioxide. That airborne sulfur dioxide provided a continuous source of sulfur for good plant growth. We can also blame some of the sulfur deficiencies to the more highly purified fertilizers being applied. Older fertilizers contained sulfur as a contaminant. Now, few high-analysis fertilizers and water-soluble fertilizers contain sulfur. However, low-analysis fertilizers such as 5-10-10 or 10-10-10 are still often blended from nutrient sources contaminated with sulfates.
In plants, sulfur is very important in the synthesis of amino acids and proteins. Researchers found that the addition of sulfur to deficient soil increased the yield of seed crops such as corn and soybeans by 10 to 20 percent. The addition of sulfur was also beneficial to the growth of cold crops such as cabbage, broccoli and cauliflower. In reviewing soil test results, I have also noticed that sulfur levels in Southern Maryland are dropping.
If soil test results indicate deficient or low levels of sulfur, it can be applied in various forms: pulverized, wettable, flowable, granulated and iron sulfate. Choose from other forms as your soil test indicates.
Should your soil need phosphorus, purchase only single-strength super phosphate.
If your plants need nitrogen, purchase ammonium sulfate.
If the soil is in need of potassium, purchase potassium sulfate.
If your soil needs calcium, purchase calcium sulfate.
If the soil is in need of magnesium, purchase Epsom salts.
Compost made from organic waste harvested from areas low in sulfur will also be low in sulfur. However, compost made from seafood waste or biosolids will be rich in sulfur. The nutrients in compost are totally dependent on nutrients in the feedstock being composted.
You do not want to add sulfur if you are growing onions and garlic, as it will increase their sharpness in flavor. To grow mild onions, select a soil that contains nearly deficient levels of sulfur. Vidalia onions — grown only in Vidalia County, Georgia — are mild because their soils contain very low levels of sulfur.
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